As-triazino(5,6-b)indoles



United States Patent 3,467,657 AS-TRIAZINO[5,6-b]INDOLES Jan Mieczyslaw Zygmunt Gladych, Hertford, and John Harold Hunt, Theydon Bois, England, assignors to Allen and Hanburys Limited, London, England No Drawing. Original application Aug. 7, 1967, Ser. No. 658,644. Divided and this application July 16, 1968, Ser. No. 745,126 Claims priority, application Great Britain, Sept. 17, 1963, 36,551/63; Feb. 20, 1964, 7,168/64; Aug. 27, 1964, 35,190/64; July 18, 1967, 33,050/67 Int. Cl. C07d 55/10; A01n 9/22 US. Cl. 260249.5 8 Claims ABSTRACT OF THE DISCLOSURE As-triazino[5,6-b1indoles of the formula:

where R is hydrogen, halogen, alkyl of 1-5 carbon atoms and preferably alkyl of 14 carbon atoms, hydroxy, alkoxy, nitro, amino or trifiuoromethyl; R is hydrogen, lower alkyl of l-S carbon atoms and preferably alkyl of 1-4 carbon atoms, benzyl or phenethyl; X is oxygen, sulphur, S0, or S and Z is hydrogen, lower alkyl of 1-5 carbon atoms and preferably alkyl of 1-4 carbon atoms, or lower alkenyl of 35 carbon atoms, provided that when X is S0 or 80;, Z is not hydrogen, exhibit antiviral activity.

N-oxide derivatives with a N- O group and pharmaceutically acceptable non-toxic salts are also within the scope of the above compounds. Particularly valuable compounds are those substituted in the 3-position with mercapto or methylmercapto moieties.

This application is a divisional-continuation-impart of Ser. No. 658,644, filed Aug. 7, 1967, which is a continuation-in-part of Ser. No. 396,727, filed Sept. 15, 1964, now abandoned.

The present invention is concerned with novel hetercyclic compounds. More particularly, the present invention is concerned with as-triazino[5,6-b]indoles of the general formula:

9 8 2N Ih- {fig-H 3,467,657 Patented Sept. 16, 1969 N-oxide derivatives with a N+O group are also a part of the present invention as well as pharmaceutically acceptable non-toxic salts of the as-triaZino[5,6-b]indoles, of the general formula shown above. Some compounds of Formula I, e.g., the 3-mercaptoand 3-hydroxy-as-triazino [5,6-b]ind0les, of Formula I, are weak acids and form stable alkali salts. All types of pharmaceutically acceptable salts are included within the scope of the invention.

As discussed above, all the compounds of this invention are characterized by the presence of an as-triazino- [5,6-b]indole nucleus and differ in the nature of the substituents R R X and Z. Thus, the invention comprises a first group of compounds in which X is S and Z is hydrogen, alkyl or alkenyl. This group comprises substances with a free mercapto or its tautomeric thione form or a substituted. mercapto or thio group, for instance, 3-mercapto-as-triazino 5,6-b] indole,

3 -merca-pto-5-methyl-as-triazino [5 ,6-b indole,

3 -mercapto-5 -ethyl-as-triazif1o 5 ,6-b] indole, 3-n1ercapto-S-propyl-as-triazino[5,6-b indole,

3 -mercapto-5-methyl-8-nitro-as-triazino[5,6-b1indole,

3 -mercapto-5- methyl-8-chloro-as-triazino[ 5,6-b] indole, 3-mercapto-8-nitro-as-triazino [5,6-b] indole, 3-mercapto-8-methoXy-as-triazino[ 5,6-b] indole, 3-mercapto-5-methyl-8-bromo-as-triazino[5,6-b]indole, 3 -mercapto-7-rnethoxy-as-triazino [5,6-b] indole, and 3-mercapto-S-propyl-8-chloro-as-triazino[5,6-b] indole.

Among the substituted mercapto compounds there may be mentioned 3 -methyl mercapto-as-triazino 5,6-b] indole,

3 -methylmercapto-S-methyl-as-triazino [5 ,6-b] indole,

3 -methylmercapto-5-methyl-8-chloro-as-triazino 5,6-b]

indole,

3-methylmercapto-5-propyl-as-triazino[5,6-b]indole,

3-methylmercapto-5-methyl-8-nitro-as-triazino [5,6-b]

indole,

3-methylmercapto-5-propyl-8-chloro-as-triazino[5,6-b]

indole,

3 -ethylmercapto-as-triazino [5,6-b] indole,

3-ethylmercapto-5-rnethyl-as-triazino[5,6-b]indole,

3-allylmercapto-S-methyl-as-triazino 5,6-b] indole,

3-ethylmercapto-S-propyl-as-triazino [5,6-b] indole,

the dodecyl iodide of 5-methyl-3-methylmercapto-as-triazino[5,6-b]indole, the propiodide of 5-methyl-3-methylmercaptcras-triazino[5,6-b1indole and the methiodide of 5-methyl-3-methylmercapto-as-triazino [5,6-b indole.

The second group of the compounds of this invention, falling within the scope of Formula 1, comprises compounds with an hydroxyl group or a substituted hydroxyl group in the 3-position. More specifically, there may be mentioned 3-hydroxy-as-triazino[5,6-b]indole and 3-hydroXy-S-methyl as triazino[5,6-b1indole. Ether derivatives also fall within the scope of the compounds of this invention, such as for instance, 3-methoxy-S-methyl-astriazino[5,6-b1indole.

The third group of the compounds of Formula I comprises compounds wherein X in the general formula is the S0 or the S0 radical. For instance, there may be mentioned 3-methylsulphonyl-S-methyl-as-triazino[5,6-b1indole,

3-ethylsulphonyl-S-rnethyl-as-triazino 5,6-b] indole,

3 -methylsulphonyl-5-methyl-8-nitro-as-triazino] 5,6-b]

indole, and

3 3-methylsulphonyl-5-methyl-8-nitroas-triazone[5,6-b]

indole.

The compounds of Formula I in which a mercapto group or a substituted mercapto group is present in the 3-position, may be prepared by the cyclization of isatin B-thiosemicarbazones of the general formula -IJ.IJII.C1S.IIII2 wherein R and R have the meanings given above, to give 3-mercapto-as-triazino[5,6-b]indoles of the general formula (III) wherein R and R have the meanings given above and, if desired, converting the compounds of Formula III to other compounds of Formula I by conventional methods.

The thiosemicarbazones of Formula II may be cyclized to give the compounds of Formula III by, for example, refluxing in the presence of ammonia or aqueous potassium carbonate. Alternatively, the thiosemicarbazones need not be isolated in which case thiosemicarbazide and the isatin of formula wherein R and R have the meanings given above, are refluxed together in aqueous potassium carbonate solution.

The compounds of Formula III are converted to other compounds of Formula I by conventional methods, that is, by methods known in the art for converting a SH radical into other radicals of the general Formula XZ, wherein X and Z have the meaning given above. For instance, a 3-mercapto-as-triazino [5,6-b]ind0le of Formula III may be reacted with an alkylating agent, in order to replace the hydrogen of the SH group with an alkyl or alkenyl group. An example of a suitable agent is a simple alkylating agent such as dimethyl sulphate. Preferably the S-mercapto-as-triazino[5,6-b]indole of Forcmula III is condensed with the alkylating agent in the presence of an alkaline condensing agent such as sodium hydroxide or a sodium alkoxide. The compound of Formula III can also exist in the tautomeric structure, that is with the thione group, C:S, in the 3-position.

The compounds of Formula I in which X is an oxygen atom may be prepared by known methods. For instance, 3-hydroxy-as-triazino[5,6-b]indoles may be prepared by known methods for converting mercapto groups to hydroxy groups. For example, 3-mercapto-as-triazino[5,6- b]indoles of Formula III may be reacted with alkaline hydrogen peroxide or chloroacetic acid. -'Ethers of 3-hydroxy-as-triazino[5,6-b1indoles may be prepared by methods known in the art.

If desired, the basic compounds of Formula I obtained by any of the processes given above may be quaternized or converted into their salts with inorganic or organic acids and the acidic compounds of Formula I may be converted into their salts with bases.

Compounds of Formula I in which X is S0 or a S0 and Z is as defined above, except H, i.e., sulphoxides and sulphones, may be prepared by oxidation of compounds of Formula V below, with, for example, acidified potassium permanganate.

For the purpose of further illustration of this invention, the following examples are set forth in detail below.

1.-Preparation of 3-mercapto-5-methyl-astriazino[5,6-b] indole (a) 6.0 g. of N-methylisatin thiosemicarbazone was suspended in 1.5 l. of water containing 15 ml. of ammonia solution of sp.g. 0.880 and the mixture was boiled under reflux for 24 hours. After cooling, a small amount of insoluble material was removed by filtration and discarded. The filtrate was evaporated under reduced pressure to about one third of its volume and, after cooling, the yellow solid which separated was filtered ofl? and recrystallized from aqueous dimethyl formamide; 3 mercapto 5 methyl as triazino[5,6-b]indole was obtained, M.P. 279281 C.

The following compounds were prepared in a similar manner:

Example 3-mercapto-as-triazino[5,6-b]indole,

M.P. higher than 360 C.

3-n1erca pto-5 -ethyl-as-triazino [5 ,6 -b] indole,

M.P. 294 C.

3-mercapto-5-propyl-as-triazino [5,6-b] indole,

M.P. 278 C.

(b) 5 g. of N-methylisatin thiosemicarbazone was suspended in 100 ml. of water containing 4.4 g. of potassium carbonate and the mixture was boiled under reflux for minutes. The orange colored solution was cooled, diluted with ml. of water and acidified with acetic acid. The yellow solid which separated was filtered off, washed with water, dried at 100 C. and recrystallized from a large volume of methanol to give 3-mcrcapto-5- methyl-as-triazino[5,6-b], M.P. 278 to 282 C.

The following compounds were prepared in a similar manner:

3-mercapto-as-triazino 5 ,6-b] indole,

M.P. higher than 360 C. 3 mercapto-5-methyl-Z-chloro-as-triazino [5,6-b indole,

M.P. 315 to 316 C. 3-mercapto-8-nitro-as-triazino[5,6-b] indole,

M.P. higher than 350 C. 3-mercapto-S-methoxy-as-triazino [5 ,6-b] indole M.P. 331 C. 3 -mercapto-5-methyl-S-bromo-a s-triazino 5,6-b] indole,

M.P. higher than 350 C. 3 -mercapto-5-methyl-8-nitro-as-triazino [5,6-b] indole,

M.P. 283 C.

(c) 16 g. of N-methylisatin, 10 g. of thiosemicarbazide and 21 g. of potassium carbonate were boiled under reflux in 500 m1. of water for 7 hours. A small amount of insoluble material was removed by filtration and discarded and the filtrate was cooled and acidified with acetic acid. The solid which separated was filtered off, washed with water and dried at 100 C. to give 3-mercapto-S-rnethyl-as-triazino[5,6-b]indole, M.P. 275 to 281 C.

The following compounds were prepared in a similar manner:

3-mercapto-7-methoxy-as-triazino 5,6-b] indole,

M.P. 309 C.

3 -mercapto-5-propyl-8-chloro-as-triazino[5,6-b1indole,

M.P. 270 to 275 C.

Example 2.Preparation of 3-methylmercapto-5-propylas-triazino[5,6-b]indole 3 g. of 3-mercapto-5-propyl-as-triazino[5,6-b]indole was dissolved in 25 ml. 1 N sodium hydroxide. 1.4 ml. of dimethylsulphate was added in several portions while shaking during minutes. The mixture was allowed to stand for 1% hours and was then poured into 250 ml. of water. The yellow solid was filtered off and recrystallized from ethanol, after discarding a small amount of insoluble material. The product had M.P. 129 to 130 C.

The following compounds were prepared in a similar manner:

3-methylmercapto-as-triazino[5,6-b]indole, M.P. 314 C. 3-methylmercapto-S-methyl-as-triazino [5,6-b1indole,

M.P. 185 C. 3-methylmercapto-5-methyl-8-chloro-as-triazino[5,6-b]

indole, M.P. 237 C. 3-methylmercapto-S-methyl-S-nitro-as-triazino[5,6-b]

indole, M.P. 251 C. 3-methylmercapto-5 -propyl-8-chloro-as-triazino [5 ,6-b]

indole, M.P. 187 C. 3-ethy1mercapto-as-triazino[5,6-b]indole, M.P. 303 C. 3-ethylmercapto-5-methyl-as-triazino 5,6-b] indole, M.P.

154 C. 3-allylmercapto-5-methyl-as-triazino[5,6-b]indole, M.P.

Example 3.--Preparation of 3-methylsulphonyl-S-methylas-triazino [5 ,6-b] indole 2 g. of 3-methylmercapto-S-methyl-as-triazino[5,6-b] indole was dissolved in 100 ml. of 5 N aqueous sulphuric acid and the solution was treated with 36 ml. of 3% solution of potassium permanganate. An immediate brown precipitate was produced which on standing for 12 hours became pale yellow. The mixture was poured into water and the yellow solid was removed by filtration and recrystallized twice from ethanol. The sulphone so obtained had M.P. 224 C.

The following compounds were prepared in a similar manner:

3-ethylsulphonyl-5-methyl-as-triazino[5,6-b]indole,

M.P. 175 C.

3-methylsulphonyl-S-methyl-8-chloro-as-triazino 5,6-b]

indole, M.P. 231 C.

3-methylsulphonyl-5-methyl-8-nitro-as-triazino 5,6-b]

indole, M.P. 236 C.

Example 4.-Preparation of 3-hydroxy-as-triazino [5,6-b1indole 1 g. of 3-mercapto-as-triazino[5,6-b]indole was dissolved in 10 ml. of 10% NaOH, and 6 m1. of hydrogen peroxide, 100 vol., was added in small portions, with shaking. After the initial vigorous reaction subsided, the mixture was refluxed for 1% hours, cooled, and acidified with glacial acetic acid. The yellow solid which precipitated was filtered off and Washed with water and acetone. Recrystallization from dimethylformamide gave the product as yellow crystals, M.P. above 380 C.

Example 5.-Preparation of 3-hydroxy-5-methy1-astriazino[5,6-b]indole 5 g. of 3-mercapto-5-methyl-as-triazino[5,6-b]indole was dissolved in 65 ml. of 10% sodium hydroxide and cooled in ice. To the red solution was added, dropwise with stirring, 30 ml. of 30% hydrogen peroxide. When the vigorous reaction had subsided, the yellow mixture, was stirred for 50 minutes, then diluted with water and acidified with acetic acid. The yellow solid was filtered oif and recrystallized from pyridine, M.P. 345 C.

Example 6.--Preparation of the methiodide of S-methylmercapto-5-methyl-as-triazino [5,6-b] indole A solution of 2.3 g. of 3-methylmercapto-S-methyl-astriazino[5,6-b]indole in 25 ml. of ethyl methyl ketone and 3.5 ml. of methyl iodide was boiled under reflux for 6 hours. A sticky reddish brown solid deposited which later hardened. It was filtered ofl, washed with acetone. Crystallized from a mixture of 30 ml. of ethanol and 15 ml. of ether, it gave 2 g. of red crystals, M.P. 203 to 204 C.

Example 7.Preparation of the propiodide of S-methyl- 3-methylmercapto-as-triazino[5,6-blindole 2.3 g. of 5-methyl-3-methylmercapto-as-triazino[5,6-b] indole, 5 ml. of n-propiodide and 25 ml. of methyl ethyl ketone were boiled under reflux for 7 /2 hours. After cooling, the red solid was filtered off, Washed with acetone and recrystallized from a mixture of 15 ml. of ethanol and 30 ml. of ether, to give the product as orange microcrystals, M.P. 166 to 167 C.

Example 8.Preparation of the dodecyl iodide of 5-methyl-3-methylmercapto-as-triazino[5,6-b]indole 4.4 g. of 5-methyl-3-methylmercapto-as-triazino[5,6- b]indole were boiled with 11.8 g. of dodecyl iodide in 70 ml. of methyl ethyl ketone for 30 hours. After cooling, the red solid was filtered off, washed with acetone and recrystallized from a mixture of 30 ml. of ethanol and 140 ml. of ether, to give the product as orange microcrystals, M.P. 161 to 164 C.

Example 9.Preparation of 3-methoxy-5-methyl-astriazino [5,6-b] indole A solution of 7 g. of sodium in 250 ml. of dry methanol Was added to 17.25 g. of 3-methylmercapto-S-methyl-astriazino[5,6-b]indole and refluxed with stirring for 1% hours, while methylmercaptan was evolved. The solution was cooled and the solid which separated was filtered oif and dried. Recrystallization from isopropanol after filtration of an insoluble product, gave 5.2 g. of the 3-methoxy 5 methyl as triazino[5,6 b]indole as pale green needles, M.P. 149 to 151 C.

Several methods have been used for testing the antiviral activity of the compounds of the invention. The general method consists of adding each dose of the compound under test to 8 tubes of confluent cells, adding 16 hours later, a TCD challenge of a virus to 4 of the tubes, the other 4 being kept for cytotoxicity controls. With each group of samples 10 tubes are kept as normal tissue controls and 10 are infected with 100 TCD of virus. After 72 hours the tubes are read microscopically for evidence of virus cytopathic eifect.

Using the above test method it has been found that 3 methylmercapto-5-propyl-as-triazino[5,6-blindole and 3-ethylmercapto-as-triazino[5,6-b]indole possess activity against Coxsackie virus A. 21.

Rhinovirus and Vaccinia virus are the agents selected for further study. The results of the tests are reported below. 1 Antiviral activity against Rhinovirus in a tube dilution test.-Tube cultures of diploid human embryonic lung (WI-26) cells were obtained from Baltimore Biological Laboratories in Eagles Minimum Essential Medium with 10% fetal calf serum.

The medium was aspirated off the cultures and replaced with 1 ml. of growth medium [Eagles Minimum Essential Medium with non-essential amino acids, prepared as described by Eagle, Science, 130, 432 (1959)] and 10% fetal calf serum. The medium of paired cultures was supplemented with 500, 100, 20 and 4'y/ml. of the compound under test. Four cultures were used as un phology observed in unstained cultures at 100x magnification. The maximum compound concentration providing no indication of toxicity in either of the two cultures was the maximum well-tolerated concentration.

The tube cultures described above were then used for the activity determination. Five-tenths ml. of an appropriate dilution of virus in growth medium containing 10 TCID (tissue culture infective dose, that is, dose causing infection of 50% of the cultures) were added to 40 cultures. Five-tenths ml. of growth medium were added to four cultures to be used as cell controls. The cultures were then incubated at 34 C. Excess virus or growth medium was removed after 1 hour and 1 ml. of growth medium was added to each culture. Four non-infected cultures used as cell controls and eight infected cultures used as virus controls were maintained in unsupplemented medium. Eight infected cultures were used to determine the anti-viral activity of each compound concentration: these received 1, /s, and WTD (well tolerated dose) of test compound diluted with the growth medium. The cultures were rolled at 34 C. The cultures were examined microscopically after four days and scored on the basis of extent of cytopathic effect. 1059, HGP and 33,342 in the table below designate particular strains of Rhinovirus.

The therapeutic ratio stated is the maximum concentration of compound tolerated by the cultures over the minimum concentration which inhibits cell destruction by the virus.

to produce granules which are dried and then passed through a screen to produce B.S. mesh granules. The dried granules are mixed with 300 g. of maize starch, 800 g. of microcrystalline cellulose, 6 0g. of polyethylene glycol 4000 and 60 g. of magnesium stearate. The lubricated granules are compressed on a suitable tabletting machine to produce tablets each weighing 500 mg. and containing 0mg. of 3-methylmercapto-5-propyl-as-triazin0[5,6-b]indole.

In a similar manner tablets are prepared from the compounds of Examples 1 and 2.

Example 12.Nasal suspension Example 13.3-rnercapto-5-methyl-8-butoxy-as-triazino [5,6-b]indole To a stirring mixture of 16.5 g. (0.1 m.) of p-butoxyaniline in 48 cc. benzene and 36 cc. water containing 3.75

Particularly favorable results were obtained with compounds 1455 and 1691. Compound 1455 was also active in the vaccinia tissue test for plaque inhibition, in the vaccinia mouse tail test at 100 mg./kg. orally, and against mouse encephalitis at 400 rug/kg. subcutaneously.

The compounds of the invention may be formulated for use in a manner well known to pharmaceutical chemists by combining them with standard pharmaceutical excipients to form tablets, capsules, ointments and intranasal preparations. The oral formulations may contain between 100 mgs. and 1 g. and may be administered 1-4 times daily.

The preparation of these pharmaceutical compositions is illustrated below.

Example l0.Capsules 300 kg. of one of the compounds of this invention, for instance 3 mercapto-5-methyl-as-triazino[5,6-b]indole, are finely divided in a comminuting mill to produce a B.S. mesh powder. This powder is filled into No. 1 hard gelatin capsules so that each capsule contains 300 mg. of the active ingredient.

In a similar manner, capsules are prepared from the compounds of Examples 1 and 2.

Example 11.-Tablets 3.00 kg. of one of the compounds of this invention, for example 3-rnethylmercapto-S-propyl-as-triazino[5,6-b] indole, 300 g. of maize starch, 400 g. of lactose and 80 g. of hydrolyzed gelatin are mixed together, then sufficient distilled water is added to produce a damp cohesive mass. The mass is passed through a. 16 B.S. mesh screen g. NaOH was added dropwise 9.6 g. of acetic anhydride. Temperature was kept between 3035 C. with an ice bath. After addition the mixture was stirred at room temperature for 0.5 hour. The precipitated white crystalline solid was collected, washed with cold benzene and dried. The product p-butoxyacetanilide weighed 20.3 g. (98.8% yield), M.P. was ll0-112 C. It was used further without purification.

To a hot solution of 20.7 g. (0.1 m.) of p-butoxyacetanilide in 200 ml. of dry toluene was added portionwise 4.9 gm. of sodium amide over a 20 minute period. Evolution of NH was noted. After a 2 /2 hour reflux, the heat source was removed and 12.6 g. (0.1 In.) of dimethyl sulfate was added dropwise. Contents were refluxed again for 0.5 hour and poured into 200 ml. of water. The organic layer was separated and dried over MgSO After concentration in vacuo, 20.5 g. (-92%) of liquid residue was obtained. This was immediately hydrolyzed as described below.

A solution of 20.5 g. (0.092 m.) of p-butoxy-N-methylacetanilide in 81 cc. of ethanol and 9 cc. of water containing 22.5 g. KOH was refluxed for 17 hours. Alcohol was removed in vacuo and the aqueous mixture extracted with benzene. The organic layer was dried and concentrated in vacuo leaving 13.3 g. of brown liquid residue. Distillation at 96102 C./0.2 mm. gave 11.3 g. (69% purified yield) of p-butoxy-N-rnethylaniline.

To a solution of 8.6 g. (0.043 rn.) of p-butoxy-N-mcthylaniline in 32 ml. of dry benzene containing 3.5 g. of dry pyridine was added dropwise 6.12 g. (0.048 m.) of ethyl oxalyl chloride. The mixture was refluxed for 0.5 hour, the pyridine-HCl salt was removed by filtration and the clear filtrate was concentrated in vacuo to give 14.3 g. of crude yellow residue. The fraction boiling at 145 -150 C./0.5 mm. was collected. It weighed 11.3 g., giving a 94% yield of pbutoxy-N-methyl-N-ethyloxalyl aniline, which was then cyclized to the isatin.

To a solution of 11.3 g. (0.04 m.) of the above in 46 ml. of carbon tetrachloride was added portionwise 8.37 g. (0.04 m.) of phosphorus pentachloride. The mixture was stirred at room temperature for 45 minutes, then the yellowish solution was concentrated in vacuo and the viscous residue was poured on crushed ice. The red oily product was extracted with chloroform and dried over MgSO After concentration, 10 g. of red viscous S-butoxy-N- methylisatin was obtained.

9 g. (0.038 m.) of S-butoxy-N-methylisatin and 3.8 g. of thiosemicarbazide in 250 cc. of water containing 11.8 g. K were refluxed for 19 hours. The deep red solution was filtered from insolubles and acidified with glacial acetic acid. The precipitated orange solid was collected and dried. The 3-mercapto-5-methyl-S-butoxy-as-triazino- [5,6-b1indole weighed 6.4 g. giving a 59% yield. After recrystallization from methanol-dimethylformamide, it gave a M.P. of 251.5253.5 C.

Example 14.-3amethylmercapto-8-bromo-5-methyl-astriazino[5,6-b]ind0le To a stirred suspension of 2.3 g. (0.01 m.) of S-bromoisatin in 25 ml. of methanol was added ml. of 10% methanolic KOH followed by 1.5 ml. of dimethyl sulfate. Stirring at room temperature was continued for 45 minutes. The white potassium methyl sulfate salt was removed by filtration and the clear red filtrate was concentrated in vacuo. The solid residue was triturated with aqueous alcohol and filtered off to give 1.65 g. (68.8% yield) of S-brorno-N-methylisatin. After purification from ethanol the deep orange needles melted at 164-166 C.

A mixture of 0.5 g. (0.002 m.) of S-bromo-N-methylisatin, 0.2 g. (0.0022 111.) of thiosemicarbazide and 0.6 g. of K CO in 25 ml. of water was refluxed for 4 /2 hours. Complete solution resulted. The resulting solution was filtered hot from any insolubles, cooled and acidified with glacial acetic acid; 0.55 g. of orange solid was obtained (93% crude yield). It was recrystallized from CH CN- MeOH mixture to give Orange needles of 8-bromo-3-mercapto-5-methyl-as-triazino[5,6-b]indole, melting at 289- 291 C.

To a partial solution of 14.5 g. (0.049 rm.) of 3-mercapto- S-methyl-8-brom-o-as-triazino[5,6-b]indole in 140 ml. of 1 N NaOH was added 2.8 ml. of methyl iodide'. The mixture was stirred at room temperature for 45 minutes. The yellow solid was collected. It weighed 11.8 g., giving a 78% yield. It was recrystallized from a large volume of ethanol to give fine yellow needles of the 3-methylmercapto compound, melting at 250 -252 C.

Example 15.-3-methylmercapto-5-methyl-8-fluoro-astriazino[5,6-b]indole A stirred mixture of 5.8 g. (.0324 m.) of l-methyl-S- fluoroisatin, 3.25 g. (.0358 m.) of thiosemicarbazide, 5.6 g. of anhydrous potassium carbonate, and 650 ml. of water was heated under reflux for 5 hours, cooled, filtered, and the filtrate was acidified with glacial acetic acid. The precipitated yellow solid was filtered 01f, washed with water, and dried. Yield, 7.6 g. (quant), M.P. 300305 C. (dec.).

An analytical sample of the 3-mercapto-5-imethyl-8- fluorotriazinoindole was recrystallized from aqueous dimethylformamide, M.P. 308310 C. (dec.).

To a stirred, cooled (0-5") solution of 1.17 g. (.005 m.) of the above 3-mercapto-5-methyl-8-fluoro-as-triazino[5, 6-b]indole in ml. of 1 N sodium hydroxide was added in one portion 0.4 ml. (0.91 g., 0.0064 In.) of methyl iodide. After 1-2 minutes a solid began to form. The cooling bath was removed, and the reaction mixture was stirred for 2.5 hours. The yellow solid was filtered off, washed 10 with water, and dried. Yield 1.15 g. (93%), M.P. 208- 212 C.

An analytical sample of the S-methylmercapto compound was recrystallized first from aqueous acetic acid and then from acetonitrile, M.P. 214215 C.

Example 16.3-mercapto-S,8-dimethyl-as-triazino[5,6-b] indole 1,5dimethylisatin (2.0 g.), 1.25 g. of thiosemicarbazide and 1.94 g. of potassium carbonate were refluxed in 400 ml. of water for 6 hours. The clear yellow solution was acidified with glacial acetic acid and the yellow 3-mercapto-S,8-dimethyl-as-triazino[5,6-b]indole collected, M.P. 299-301 C.

Example 17.3-methylmercapto-5-methyl-8-as-triazin0 [5,6-b]indole A stirred mixture of 3.50 g. (.0161 m.) of l-methyl-S- butylisatin, 1.62 g. (.0178 m.) of thiosemicarbazide, 2.8 g. of potassium carbonate, and 370 ml. of water was heated under reflux for 5 hours. The cooled reaction mixture was clarified by filtration, and the filtrate was acidified with glacial acetic acid. The precipitated yellow 3- mercapto-S-methyl-8-butyltriazinoindole was collected by suction filtration and purified by recrystallization from glacial acetic acid. Yield 2.68 g. (61% M.P. 242-244 C. (dec.).

An analytical sample was recrystallized from aqueous dimethylformamide, M.P. 243-245 C. (dec.).

To a stirred solution of 5.44 g. (.02 m.) of the above 3-mercapto 5-methyl-8-butyl-as-triazino[5,6-b]indole in 60 ml. of l N sodium hydroxide and 50 ml. of ethanol was added in one portion 16 ml. (3.62 g., .0255 m.) of methyl iodide. There was a mildly exothermic reaction and a precipitate formed immediately. After stirring for 2 hours, the crude 3-methylmercapto product was collected by suction filtration, and purified by recrystallization from ethanol, using Norit A decolorizing carbon. Yield 4.0 g. (70%), M.P.138139 C.

Example l8.3-methylmercapto-5-methyl-8rmethoxyas-triazino [5 ,6-b] indole 5-me'thoxy-N-methylisatin (0.5 g.), 0.263 g. of thiosemicarbazide and 0.447 g. of potassium carbonate were suspended in ml. of water and refluxed for 20 hours. Upon acidifying the clear yellow-orange solution an orange solid precipitated. (3-mercapto-5-methyl-8-methoxy-as-triazino[5,6-b]indole); M.P. 310312 C.

Methyl iodide (2.9 ml.) was added to a cooled (ice bath) solution of 8 g. of 3-mercapto-5-methyl-8-methoxyas-triazino[5,6-b]indole in 120 ml. of 1 N NaOH. After 1 hour stirring at room temperature the green solid was isolated (3 methylmercapto-5-methyl-8-methoxy-as-triazino[5,6-b]indole); M.P. l64l67 C.

Example 19.3-mercapto-5-methyl-8-hydroxy-as-triazino [5,6-b1indole 3 mercapto 5-methyl-8-methoxy-as-triazino[5,6-b]indole (1.0 g.) was refluxed in 2 0 ml. of 48% HBr for 1% hours under an atmosphere of nitrogen. A yelloworange solid was recovered (3-mercapto-5-methyl-8-hydroxy-as-triazino[5,6-b]indole, M.P. 312-314 C.

Example 20.3-mercapto-S-methyl-8-trifluoromethyl-astriazino [5,6-b] indole To a stirred 500 cc. three-neck flask were added the following: 9.0 g. (0.054 m.) of chloral hydrate in 60 ml. water, 120 g. of crystalline sodium sulfate, 8.76 g. (0.05 m.) of p-trifluoromethyl-N-methylaniline (prepared by treating p-trifluoromethyl bromobenzene with 5 equivalents of methylamine in a steel bomb at for 8 hours) dissolved in 30 ml. of water containing 4.2 cc. of concentrated HCl, and finally a solution of 11.0 g. (0.158 In.) hydroxylamine-HCI in 50 ml. of water. The contents were heated to reflux with a heating mantel and refluxed while stirring for 4 minutes. The aqueous mixture was cooled and extracted with chloroform. After drying and concentration of the organic layer, 5.5 g. (41.5% yield) of an off-white solid product was obtained. It was immediately cyclized to the isatin without further purification.

A mixture of 5.5 g. (0.022 m.) of p-trifiuoromethyl- N-methylisonitrosoacetanilide and 25 cc. of concentrated H 50 was heated on the steam bath for 10 minutes and poured on crushed ice. The orange solid was collected. It weighed 3.8 g. (75.5% yield). After purification from a mixture of ethyl acetate and petroleum ether, the orange crystals of 5-trifiuoromethyl-N-methylisatin melted at 13l-133 C.

A mixture of 3.8 g. (0.016 m.) of S-trifluoromethyl- N-methylisatin in 150 cc. of water containing 1.6 g. thiosemicarbazide and 4.6 g. K 50 was refluxed for 17 hours. The dark amber solution was filtered from any insolubles, cooled and acidified with glacial acetic acid. The precipitated yellow solid was collected and dried. It weighed 4.0 g. giving an 85% crude yield. It was purified from mixture of methanol and dimethylformamide giving 3-rnercapto-5-methyl-8-trifiuoro-methyl-as-triazino [5,6-b]indole, M.P. 274-276 C.

8 amino-3-mercapto-5-methyl-as-triazino[5,6-b1indole is prepared by treating the corresponding 8-bromo compound with liquid ammonia in the presence of copper powder and cuprous chloride at 110 C. for 7-8 hours in a closed pressure vessel.

We claim:

1. A compound of the formula wherein:

R is hydrogen, halogen, alkyl of 1-5 carbon atoms,

12 hydroxy, alkoxy of l-5 carbon atoms, nitro, amino, or trifiuoromethyl;

R is hydrogen, lower alkyl of l5 carbon atoms, benzyl,

or phenethyl;

X is oxygen, sulfur, S0, or S0 and Z is hydrogen, lower alkyl of 1-5 carbon atoms, or

lower alkenyl of 3-5 carbon atoms, provided that when X is S0 or S0 is not hydrogen; or a pharmaceutically acceptable non-toxic salt thereof.

2. A compound as claimed in claim 1, in which R is hydrogen or lower alkyl of 1-5 carbon atoms, X is sulfur, and Z is hydrogen or lower alkyl of l-5 carbon atoms.

3. A compound as claimed in claim 2, in which R is hydrogen and is in the 8-position.

4. A compound as claimed in claim 3, which is 3- methylmercapto-5-propyl-as-triazino [5,6-b] indole.

5. A compound as claimed in claim 3, which is 3-mercapto-5-methyl-as-triazino[5,6-b]indole.

6. A compound as claimed in claim 3, which is 3-ethylmercapto-5-methyl-as-triazino[5,6-b]indole.

7. A compound as claimed in claim 1, which is 3-n1ercapto-S-methyl-8-butoxy-as-triazino[5,6-bjindole.

8. A compound as claimed in claim 1, which is 3-mercapto S-methyl 8-trifluoromethyl-as-triazino[5,6-b]indole.

References Cited HENRY R. JILES, Primary Examiner JOHN M. FORD, Assistant Examiner US. Cl. X.R. 

